Heat exchanger for separating out constituents from a gas by cooling



Aug 2 1960 v A. T. BLOEM 2 HEAT EXOHANGER FOR SEPARATING OUTOONSTITUENTS 947152 FROM A GAS BY COOLING Filed Oct. 29, 195e 1C@Patented Aug. 2, 1960 HEAT EXCHANGER FOR SEPARATING oUT CoN- sTrTUEN'rsFROM A ons YcooLrNo Aldert Teunis Bloem, Eindhoven, Netherlands,assgnor,

by mesne assignments, to North American Philips Company, Inc., New York,N.Y., a corporation-of Delaware Filed Oct. 29, '1956, Ser. No. 618,794

Claims priority, application Netherlands Nov. 6, 1955 `4 Claims. (ci.62-40) The invention relates to heat exchangers for separatingconstituents from a'gas by means of cooling, which heat exchangers areprovided with an Kaperture for supplying the gas and an aperture fordischarging the gas and a number of projections arranged in the path ofthe gas, which are mounted on a common supporting member, there beingduring the operation of the heat exchanger in at least a number .ofthese projections or groups of projections a decrease in the meantemperature of at the most 20 C. between adjacent projections oradjacent groups of projections, commencing from the hot side to the coldside. The term gas las used herein is to be understood to mean also avapour or a gas mixture.

Such a heat exchanger may, for example, be used for removingwater Vapourand carbon dioxide from air. This may' be required when `air is to befractionated or condensed. However, other gases also, for examplenatdependent of circumstances relating to the iluid itself, that is tosay independent of the amount of uid supplied or of the fractions ofwhich it consists.. In this case particularly, according to a furtherembodiment Vof the invention the supporting member may have one side inheatexchanging contact with a cooling agent contained in a space. Thiscooling agent may be the working fluid of a refrigerator, for example ofa gas refrigerator;

It has also been found that, if4 the heat exchanger must remove watervapour and carbon dioxide from air, it is desirable, according to afurther embodiment of the invention, for the part of the heat exchangerintended for the water vapour to be at least substantially horizontalwhile the part intended for the carbon dioxide extends substantiallyvertically.

The invention will now be described more fully with reference to somevembodiments thereof.

ural gas, have constituents whichcan be removed-by freezing out; In heatexchangers of this vkind the separa`l tion products accumulate in theheat exchanger, sothat this gets clogged sooner or later.

separation products, for example by heating, the heat exchanger canagainbe put in operation. The time required to remove the impurities isvwasted and itis an object of the present invention to provide a designfor a heat exchanger of the above-mentioned kind such that compared'with the 'known heat exchanger a larger amount of impurities can befrozen out.

According to the invention, at least a number of the l projectionsarranged in the path of the gas have a thermal the known heat exchangersin which there is no such temperature difference along the projections.As will be explained more fully hereinafter, this appreciabletemperature difference enables a greater -amount of impurities to bestored in the heat exchanger than would be the case without thistemperature difference. Preferably, the temperature difference along aprojection is not excessively large, for example does no-t exceed 30 C.,since otherwise the heat exchanger may occupy too much space. In astructurally simple embodiment, the projections are pins.

The supporting member may be a partition between two spaces in whichfluids having different temperatures flow. This is, forrexample, thecase when a gas mixture to be fractionated is in heat-exchanging contactwith at least one of the fractions produced. However, in certain casesit may be desirable for the amount of thermal energy which is withdrawnfrom the gas or the gas mixture to be in- After removal of the Fig. 4ris a cross-sectional view takenalong the line lV-IV of Fig. 3. Y

Fig.v 5 shows a heat exchanger, of which part extends substantiallyhorizontally and part 'substantially vertically.

The heat exchanger shown in Figures 1 vand 2 comprises a supportingmember 1 provided-with projections 2, for example pins.

exchanging contact with a; cooling liquid contained in a space 7, forexample liquid nitrogen. VThe heat extracted from the gas to be cooledis supplied by way of the pins 2 and the supporting member 1v to theliquid contained in the space 7 so that this liquid evaporates, thevapour be-` ing through a pipe 8 to a refrigerator (not shown) to bere-condensed. The condensate produced by the refrgeator can again besuppliedV to the space 7` through a pipe" 9.v The refrigerator may be agas refrigeratonbut naturally any suitable refrigerator can be use Thesupporting member is made from a V'material hav-l ing a thermalresistance such that in'normal operation l there is a mean temperaturedifference of at the` most" 20 C. between the mean temperatures of thepins 2. yIn' this embodiment, the mean temperature of the series ofproject-ions 2a is at the most 10 C. higher than`t-hatuof' the series 2bwhich again is 10 C. higher than that of the series 2, etc. The meantemperature is -t'he'arithmetic mean of the temperature at an end 10 ofa projection Vand of 'the temperature at the point A111 at which aprojection is attached to the supporting member 1. The tempera" turedifference between these two points in' each projection is at least 5 C.and preferably less than 30 C., inthe embodiment shown, for example, 19C.

The System oPerates as follows: f.

blower (not shown).

dioxide.

and water is formed. At a Vgiven instant, the air flows past pins havingalready a very low temperature at their bases, so that the water vapourfrom the air after being An insulating wall 3y provides` a duct IlV forthe gas mixture, the projections `2 being disposed inthe path of thegasmixture. The heat exchanger has an inlet H apertureS land an outletaperture 6v for the gas `mixture 'to'l be cooled. One end of thesupporting member V1 is in heat' condensed on preceding pins freezes tothe bases of these pins. However, after some time such an amount of ice12, which is shown by broken lines in Fig. 1, is frozen to the bases ofpins 7 that the air is forced to ilow along the tops of the pins.Consequently, a greater amount of air ilows past these parts of the pinsso that a greater amount of thermal energy is supplied to the pins. As aresult, part of the ice adhering to the pins melts and the waterproduced flows down either to be discharged or to be frozen again to thecold lower ends of the pins. The air which flows past the tops of thepins, at a point to the right-hand side of the first-mentioned pinscomes into contact with otherpins having a temperature sufficientlylov.y to cause ice to be formed, so that on the upper ends of these pinsan amount of ice 13 settles, which is shown by dot-dash lilies in thegures. When the passage at the upper ends of these pins becomes clogged,the air is forced to ow past the lower ends of the pins in this part ofthe heat exchanger. Only after the passage along these pins also hasbecome blocked, the ice separator is clogged up.

In the part of the ice separator situated further to the right-rand sideof the drawing, the carbon dioxide contained in the air can be similarlyseparated out, if required, provided the pins have a suiciently lowtemperature.

The heat exchanger shown in Figures 3 and 4 operates on the sameprinciple as described hereinbefore; parts corresponding to those ofFigures 1 and 2 are designated by like reference numerals. Here,however, the gas to be. cooled, which is supplied to the heat exchangerthrough the aperture and leaves through the aperture 6, by way of asupporting member .14 is in heat-exchanging contact with a cold luidwhich is supplied to the heat exchanger through an aperture 15 andleaves it through an aperture 16. A number of plate-shaped projections,17 provided with slits |18 are arranged on the member 14. The cold uidwhich is supplied through the aperture 115 to the heat exchanger owspast projections 19 which Iare 4also attached to the support and thus isin heatexchanging contact with the gas to be cooled. Here also, thethermal resistance of the supporting member 14 is so chosen that there4is a mean temperature difference of at the most 20 C. between theadjacent projections 17 on which the constituents of the gas areseparated out. In addition, during normal operation of the heatexchanger there is a temperature gradient of 5 C. along the length ofthe projections. This heat exchanger can be used if air to befractionated must be purified, the air being cooled by heat-exchangingcontact with one of the fractions produced in the gas-fractionatingsystem, for example nitrogen. Similarly to what has been described withreference to Fig. l, at the bases of the projections 17 having `asuflciently low temperature ice is formed, part of which subsequently,when the gas mixture is forced to How past the upper parts of theprojections, which parts, as has been described herein before, are at ahigher temperature, melts olf again. The small amount of water whichdoes not freeze can be drawn olf through small apertures 20.

In the construction shown in Fig. 5, a part 21 in which the water vapouris separated yout is slightly inclined Whereas a part 22, in which thecarbon dioxide is separated out, extends vertically. In this embodimentalso, the supporting member 1 is in heat-exchanging contact with a lluidhaving a low temperature which is contained in a space 7. On the member1 a number of pins 23 which extend to a wall 24 are arranged at an angleto this member; in this embodiment also, the temperature gradient alongeach pin is at least 5 C. Due to the inclined position of the pins, theeffective surface, with the same temperature gradient along a pin,exceeds that of pins arranged at right angles to the support, while thecorner at the transition of the parts 21. and 22 can be lled with pinsin a structurally simple manner. Generally, it will be undesirable forthe part 21 of the heat exchanger in which the water is separated out,to deviate from the horizontal position excessively, in order toprevent. the melting water from collecting on the bottom of the heatexchanger without falling on the ice when dripping olf the pins.Obviously, this dripping Water can be drawn off by the use of a specialconstruction, however, this will generally involve an additionalcomplication of the heat exchanger. There is no such likelihood for thecarbon dioxide, but on the contr-ary the gas to be cooled should movevertically in this part of the heat exchanger, so that the carbondioxide can readily escape on heating.

what is claimed is:

1. A heat exchanger for separating out constituents of a gas by coolingcomprising a hollow tube provided with an inlet and outlet for said gas,a strip-like supporting member in said tube, a plurality of projectionsin said supporting member arranged in the path of said gas and securedto only one interior Wall of said hollow tube, each of said projectionstaken from the hot side of the tube to the cold side thereof being atlthe most 20 warmer than the next succeeding projection, at least anumber of said projections having a thermal resistance such that duringoperation the ends more remote from the support are at a temperature atleast 5 C. higher than the temperature at the points of attachment ofthe respective projections to said one interior wall, a thermal sink,said supporting member being directly connected to said thermal sink.

2. A heat exchanger as claimed in cla-im 1 wherein said projections arepins.

3. A heat exchanger as claimed in claim 1 further comprising `a conduitadjacent to and in yheat exchanging contact with said hollow tube, and acooling agent traversing said conduit.

4. A heat exchanger for separating out constituents of a gas by coolingcomprising a hollow tube provided with an inlet and outlet for said gas,a strip-like supporting member in said tube, a plurality of projectionsin said supporting member arranged in the path of said gas and securedto only one interior wall of said hollow tube, each of said projectionstaken from the hot side of the tube to the cold side thereof being atthe most 20 warmer than the next succeeding projection, at least anumber of said projections having a thermal resistance such that duringoperation the ends more remote from the support are at a temperature atleast 5 C. higher than the temperature at the points of attachment ofthe respective projections to said one interior wall, said constituentsof the gas to be separated 'out being water vapor and carbon dioxide,the part of the heat exchanger intended for said water vapor beingpositioned horizontally while the part of said heat exchanger intendedfor said carbon dioxide extending substantially vertically, a thermalsink, said supporting member being directly connected to said thermalsink.

References Cited in the tile of this patent UNITED STATES PATENTS1,478,750 McElroy Dec. 25, 1923 1,561,898 Antisell Nov. 17, 19251,725,906 Gay Aug. 27, 1929 2,294,137 Spoiford Aug. 25, 1942 2,492,298Lenning Dec. 27, 1949 2,500,501 Trumpler Mar. 14, 1950 2,585,288 VanNuys Feb. 12, 1952 2,585,9112 Buschow et al. Feb. 19, 1952 2,663,170Gloyer Dec. 22, 1953 2,690,060 Legatski Sept. 28, 1956 UNITED STATESPATENT OFFICE CERTIFICATION OF CORRECTION Patent No. 2,947, l52\ August2, 1960 Aldert Teunis Bloem It is hereby certified that error appears inthe above numbered patent requiring correction and that the said LettersPatent should read as corrected below.

ln the heading to the printed specification, line 9, for "Glaimspriority, application Netherlands Nov. 6, 1955" read Claims priority,application Netherlands Nov. 5, 1955 Signed and sealed this 25th day ofApril 1961,

(SEAL) Attest:

ERNEST W SWIDER DAVID L LADD Attesting Officer l Commissioner of Patents

